How is the classification server searched?

The classification server is searched by keyword and by structure. Destatis states that WZ 2025 and its keyword index, then comprising about 35,000 keywords, stand on the classification server of the federal and state statistical offices. A keyword search takes a word or phrase that describes an activity and returns the headings to which the keyword points. A structure search walks the hierarchy from section to division to group to class to subclass, reading the titles at each level. Both searches are finding aids. Neither search assigns a code. A search result is a candidate heading.

Before a candidate is treated as a description of the activity in general terms, it must be tested in its note and in the notes for neighbouring headings. The entry for a specific unit is confirmed separately, with the register that holds it.

How does a keyword search work?

A keyword search matches words in the index to headings. The index is built from the titles, notes and descriptions in the classification, so a familiar word can point to a heading that a reader would not expect from the title alone. A keyword can also point to more than one heading, because the same word can describe activities in different headings depending on the production process or the output. Destatis describes the index as a keyword index for the classification, and this guide treats it as such: a list of pointers, not a list of decisions. A reader who stops at the first pointer, without checking the note for the heading it points to, risks adopting a heading that includes the word but excludes the activity. The note states the scope. The index states only that the word appears in connection with the heading.

Search method	Input	Result
Keyword search	Word or phrase describing the activity	Headings the keyword points to
Structure walk	Section, division, group, class, subclass	Titles at each level, in hierarchy
Note check	Candidate heading from either search	Inclusions, exclusions and cross references

The table above separates finding from checking. Finding uses the index or the structure. Checking uses the note. A complete search does both, in that order.

How does a structure walk work?

A structure walk starts at the section that covers the broad area, then narrows to the division, group, class and subclass. At each level, the reader reads the titles of the headings inside the level above, and follows the one whose title and note best match the activity as described in general terms. The walk is slower than a keyword search, and it is more reliable where a keyword is ambiguous, because it shows the neighbours of each candidate heading. Neighbours matter: an activity that sits close to a boundary will have candidate headings in more than one group or division, and the walk shows those candidates side by side. The walk also shows where a heading sits after the section letter shift, because the section letter is read in the context of the version, not alone.

How are search results tested?

Search results are tested in three ways. First, the note for the candidate heading is read in full, including inclusions, exclusions and cross references. Second, read the notes for neighbouring headings, to confirm the activity is not excluded from the candidate and included in a neighbour. Third, the correspondence row is checked where the search concerns an old code or an old title, to confirm whether the heading continued, merged, split or was renamed. A result that passes all three tests is a heading that describes the activity in general terms. A result that fails any test is not discarded silently: the failing test points to the next candidate, in the neighbour headings or in the destination headings of the correspondence row. The search ends when a heading passes all three tests, or when the searcher concludes that no heading in the published structure describes the activity as stated, and the description itself must be reframed.

What does a search not decide?

A search decides the code for no reader, and decides no tax, licensing, funding or collective agreement question. It finds headings. The entry for a specific unit is confirmed with the register that holds it. This site holds no register and decides no entry. A reader who treats a search result as an entry, without the register check, mistakes a candidate for a confirmation. The classification server is published by the statistical offices. The register entry is held by the register. Keep the two apart, and state the version beside every code found in either place.

Search by keyword or by structure on the classification server, test every candidate in its note and its neighbours, and let the register confirm the entry for the unit concerned. ”